Big: Tom Hanks and David Moscow
Although Andrew Beckett in Philadelphia is the role that would win Tom Hanks his first Oscar, many forget that he was first nominated for his truly outstanding performance as Josh Baskin in Big. Hanks plays the more physically mature version of Josh (though not technically older), having become a grown man after his true 12-year-old self (played by David Moscow) wished on a carnival machine (Zoltar!) that he was... well, you know... big. Moscow handles his portion of the role, which bookends the movie, with a fantastic adolescent awkwardness, and Hanks takes what could have otherwise been a total hackfest and delivers an incredibly layered performance.